N-苄基马来酰胺酸根合镧(Ⅲ)的合成及对PVC的热稳定作用

Heat Stabilization of Complexes of Lanthanum(Ⅲ) with N-benzyl Maleamic Acid Radical on PVC

以马来酸酐、苄胺、氯化镧、氢氧化钠为原料成功合成了N-苄基马来酰胺酸根合镧(III),通过傅立叶红外光谱(FTIR)、元素分析、热重分析(TGA)、熔点等表征了其结构与性能;通过刚果红实验、紫外-可见光谱(Uv-vis)、FTIR、TGA研究了其对聚氯乙烯(PVC)的热稳定作用。结果表明,N-苄基马来酰胺酸根合镧(Ⅲ)为白色粉末,熔点184℃,其化学组成为LaL3·H2O,N-苄基马来酰胺酸根中的羧基氧和酰胺氮与镧离子发生配位,形成螯合物。刚果红试验表明,加入LaL3·H2O后PVC的热稳定时间从4min提高到28min;UV表明,PVC在降解过程中,主要形成共轭双键为3的多烯结构,同时伴有共轭双键为4~9的多烯的生成,LaL3·H2O的加入抑制了多烯的生成;FTIR表明,LaL3·H2O的加入,抑制了C-Cl键的极性;TGA研究证明,LaL3·H2O大幅提高了PVC热降解的活化能,氮气氛中由123.46kJ/mol提高到162.60kJ/mol,空气气氛中由115.94kJ/mol提高到152.15kJ/mol,提高了PVC的热稳定性,LaL3·H2O可作为PVC热稳定剂使用。

The complex of N-benzyl maleamic acid radical and lanthanum(III) was successfully synthesized with maleic anhydride,benzyl amine,lanthanum chloride and sodium hydroxide as raw materials.Structure and properties of the complex were characterized through Fourier infrared spectrum(FTIR),elemental analysis,thermogravimetric analysis(TGA) and melting point; the effects of the complexes on the thermal stability of polyvinyl chloride(PVC) were investigated by means of Congo red test,ultraviolet-visible spectrum(Uv-vis),FTIR and TGA etc technologies.The results showed that the complex of N-benzyl maleamic acid radical and lanthanum(III) is a white powder with melting point 184 ℃ and chemical composition as LaL3·H2O,coordination of lanthanum(III) ion with the carboxyl oxygen and amide nitrogen in N-benzyl maleamic acid radical as a form of chelate.Congo red test showed that the thermal stability time of LaL3· H2O on PVC increased from 4 min to 28 min; Uv-vis shows that PVC in the process of thermal degradation generated the main form of polyene structure with 3 conjugated double bonds,at the same time with conjugated double bonds of 4 ~ 9 polyene,LaL3·H2O can inhibit the generation of polyene with 3 conjugated double bonds; FTIR showed that the addition of LaL3·H2O,inhibit the polarity of C-Cl bonds because of coordination with lanthanum(III); TGA studies have demonstrated that LaL3·H2O greatly enhances the activation energy of PVC thermal degradation,increased from 123.46kJ / mole to 162.60kJ / mole in nitrogen atmosphere and from 115.94kJ / mole to 152.15kJ / mole in air atmosphere,the thermal stability of PVC is improved.LaL3· H2 O can be used as PVC thermal stabilizer.